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Two vigils are planned to honor the student and teacher who were killed in a San Bernardino school shooting. Tony Shin reports for the NBC4 News at 6 on Tuesday, April 11, 2017. (Published Tuesday, April 11, 2017)

An 8-year-old boy shot and killed along with his teacher in a San Bernardino special-education classroom was born with a genetic condition and had survived heart surgery, a school official said Tuesday.

Jonathan Martinez had Williams syndrome, a rare disorder characterized by learning delays, mild-to-moderate intellectual disabilities and heart problems, according to Dale Marsden, superintendent of the San Bernardino City Unified School District.

"By all accounts, Jonathan Martinez was a happy child," Marsden said at a news conference.

The boy died at a hospital after being shot Monday in his classroom by the estranged husband of his teacher, Karen Smith, who also was killed. The gunman, Cedric Anderson, then fatally shot himself.

A classmate, Jeffrey Imbriani, 7, told The Associated Press that he used to talk and play soccer with Jonathan.

"I know him because one day he just walked up to me and said, 'Can we be friends?' and I said, 'Yeah,' and we've been friends ever since," he said.

Jeffrey said students got out of their chairs and ran outside with their teacher when they heard gunshots.

If you would like to donate to a GoFundMe account set up to help Jonathan Martinez, you may do so here. Note that GoFundMe deducts 7.9 percent of all funds raised in the form of platform and payment processing charges.